board: gateworks: venice: add GW7903 PMIC

The GW7903 has a BD71847 PMIC on I2C1. Adjust the model compare strings
to add it.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Reviewed-by: Fabio Estevam <festevam@denx.de>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>